1. Field of the Invention
The invention relates to an inking unit for printing presses, and preferably offset printing presses. Such printing presses typically can have a plurality of inking rollers for supplying ink to a plurality of plate-inking rollers that ink a plate on a plate cylinder. The inking rollers are generally positioned before the plate-inking rollers and supply the ink to the plate-inking rollers. The inking rollers can also be arranged so that the ink flow provided by the inking rollers is split into two directions of supply. With such a configuration, the inking rollers can, together with the plate-inking rollers, form a closed chain of rollers that enclose a space therebetween.
2. Background Information
In high-speed printing presses, the inking unit can heat up significantly during production printing of a large number of copies. As the inking unit heats up, the viscosity of the ink can be changed as a result of the fluctuations in the temperature. German Patent No. 19 53 590 A1, which corresponds to U.S. Pat. No. 3,741,115, describes an inking unit that is temperature-regulated by means of regulation of the temperature of the damping solution. This German reference utilizes a generally well-known cooling device, which is controlled through the intermediary of a temperature sensor.
In another method of controlling the temperature of an inking unit, disclosed in German Patent No. 27 59 351 C2, apparatus is provided for controlling the temperature of the printing ink. Such a device can be used in order to prevent inking fluctuations in the inking unit of the printing press.
However, the temperature sensors provided in the known apparatuses are generally provided either in the coolant circuit or directly on the ink tank itself. As such, the measured temperature values provided by such known arrangements do not directly indicate the temperature values existing in the inking unit itself. Since the inking unit provides the ink distribution necessary to provide high quality prints, any temperature fluctuations in the unit itself could adversely affect the print quality, unless such changes are quickly identified and remedied. Thus, with the known configurations for controlling temperatures, it is essentially not possible for temperature adjustments, or influences of the temperature control, to be matched precisely to the requirements of the inking unit, as the inking unit temperatures are not measured.
In summary, one aspect of the invention resides broadly in a printing press comprising a plate cylinder, damping apparatus for applying a wetting agent to at least the plate cylinder, the damping apparatus comprising a reservoir for storing the wetting agent, and an inking unit for applying ink to the plate cylinder. The inking unit has an ink reservoir for storing the ink, and the inking unit comprises a plurality of plate-inking rollers disposed in contact with the plate cylinder to apply ink to the plate cylinder, a plurality of inking rollers disposed between the ink reservoir and the plate inking rollers to transfer ink from the ink reservoir to the plate inking rollers. The plurality of inking rollers defines at least two ink supply paths for supplying ink to the plate-inking rollers at at least two locations of the plate-inking rollers, and the inking rollers and the plate-inking rollers form and substantially enclose a space therebetween. The inking unit further comprises a device for extracting air from the substantially enclosed space, a temperature sensor device for measuring a temperature of the extracted air, a device for regulating a temperature of at least one of: the inking unit, and the wetting agent, and control apparatus for receiving the measured temperature from the temperature sensor device and operating the device for regulating based on the measured temperatures of the extracted air.
Another aspect of the invention resides broadly in a method for monitoring and controlling temperature in an inking unit of a printing press, wherein the printing press includes: a plate cylinder; damping apparatus for applying a wetting agent to at least the plate cylinder, and an inking unit for applying ink to the plate cylinder. The inking unit has an ink reservoir for storing the ink, and the inking unit comprises: a plurality of plate-inking rollers disposed in contact with the plate cylinder to apply ink to the plate cylinder; a plurality of inking rollers disposed between the ink reservoir and the plate inking rollers to transfer ink from the ink reservoir to the plate inking rollers; a device for extracting air from an area adjacent the plate-inking rollers and the inking rollers; temperature sensor apparatus for measuring a temperature of the extracted air; a device for regulating a temperature of at least one of: the inking unit, and the wetting agent; and control apparatus for receiving measured temperatures from the temperature sensor device and operating the device for regulating based on the measured temperatures of the extracted air. The method comprises the steps of: transferring ink within the inking unit from the ink reservoir to the plate-inking rollers, the inking unit having a temperature; transferring wetting agent from the wetting agent reservoir to at least the plate cylinder, the wetting agent having a temperature; extracting air from the area adjacent the inking rollers and the plate-inking rollers; measuring a temperature of the extracted air with the temperature sensor device; and adjusting at least one of: the temperature of the inking unit, and the temperature of the wetting agent to bring the measured temperature into correspondence with a predetermined temperature.
A further aspect for the invention resides broadly in an inking unit for a printing press, the printing press having a plate cylinder and damping apparatus for applying a wetting agent to at least the plate cylinder, the damping apparatus comprising a reservoir for storing the wetting agent, and the inking unit for applying ink to the plate cylinder. The inking unit comprises an ink reservoir for storing the ink, a plurality of plate-inking rollers for being disposed in contact with the plate cylinder to apply ink to the plate cylinder; a plurality of inking rollers disposed between the ink reservoir and the plate-inking rollers to transfer ink from the ink reservoir to the plate-inking rollers; the plurality of inking rollers defining at least two ink supply paths for supplying ink to the plate-inking rollers at at least two locations of the plate-inking rollers; the inking rollers and the plate inking rollers forming and substantially enclosing a space therebetween; a device for measuring a temperature of air of the substantially enclosed space; apparatus for regulating a temperature of at least one of: the inking unit, and the wetting agent; and control apparatus for receiving measured temperatures from the temperature sensor device and operating the apparatus for regulating based on the measured temperatures of the extracted air.